Nature Sustainability (2022). DOI: 10.1038/s41893-022-00989-3″ width=”800″ height=”530″/> Illustration of IAD mining via the EKM and AIP mechanisms. Credit: Natural durability (2022). DOI: 10.1038/s41893-022-00989-3
Illustration of IAD mining via the EKM and AIP mechanisms. Credit: Natural durability (2022). DOI: 10.1038/s41893-022-00989-3
Rare earth elements (REE), especially heavy REE (HREE), are important in modern industry. However, conventional mining technique applies excessive use of ammonium salt leaching agents to recover HREEs from ion adsorption (IAD) rare earth deposits, which exhibit low efficiency and devastating environmental impact. on the local ecosystem.
Thus, there is a need to move from traditional “mountain scraping” mining to a new generation of green ERH mining.
Recently, a research team led by Professor He Hongping from the Guangzhou Institute of Geochemistry of the Chinese Academy of Sciences developed a new technique, electrokinetic mining (EKM), for the green and efficient recovery of REEs from from weathered crusts.
The technique places a voltage on the top and bottom of the IAD, which generates an electric field to accelerate the migration of REEs and water to the cathode.
Compared to conventional techniques, EKM achieves approximately 90% recovery efficiency, approximately 80% decrease in leaching agent usage and approximately 70% reduction in metal impurities in soils few obtained.
The study was published in Natural durability October 31.
To assess the feasibility of EKM for rare earth recovery, Professor He’s lab first performed bench-scale experiments in a homemade prototype with a simulated IAD. The results suggest that the REE recovery efficiency obtained by the EKM technique was 2.6 times higher than that obtained by the ammonium leaching technique.
Then they further conducted larger scale experiments at the kilogram (20 kg) scale in a larger EKM setup. The results were consistent with laboratory-scale experiments, i.e. the EKM technique can achieve higher recovery efficiency and requires less processing time.
Based on the successful bench-scale and full-scale experiments, they applied the EKM technique to a real (~14 t-scale) IAD via a field experiment. The results suggest that the rare earth recovery efficiency reaches more than 90% in 264 hours.
The researchers further explored the mechanisms underlying the high REE recovery efficiency of EKM. “The applied electric field that accelerates REE and water migration unidirectionally to the designated location via electromigration and electroosmosis is the key to improving the efficiency of REE recovery,” said the professor He.
Besides durability and high recovery efficiency, EKM shows selectivity for REE over other metal impurities (Al3+California2+ N / A+and K+), i.e. the collected metal impurities are decreased using the EKM technique. “We have identified a self-contained mechanism for purifying impurities during the electrokinetic process, which is based on the diversity of speed and reactivity between REEs and other active metal ions,” Prof. He said.
Gaofeng Wang et al, A green and efficient technology to recover rare earth elements from weathered crusts, Natural durability (2022). DOI: 10.1038/s41893-022-00989-3
Provided by Chinese Academy of Sciences
Quote: Electrokinetic Extraction Technology to Recover Rare Earth Elements from Weathering Crusts (November 17, 2022) Retrieved November 17, 2022 from https://phys.org/news/2022-11-electrokinetic-technology-recovering -rare-earth.html
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